Cloud Computing becomes the next generation architecture of IT Enterprise. In contrast to traditional solutions, Cloud computing moves the application software and databases to the large data centres, where the management of the data and services may not be fully trustworthy. This unique feature, however, raises many new security challenges which have not been well understood. In cloud computing, both data and software are fully not contained on the user's computer; Data Security concerns arises because both user data and program are residing in Provider Premises. Clouds typically have single security architecture but have many customers with different demands. Every cloud provider solves this problem by encrypting the data by using encryption algorithms. Even multi-tenancy feature of cloud give rise to security issue related to data and also the authentication of users. We provide a secure scheme which protects the sensitive data of the user stored in the cloud. We solve the problem which existing systems faces with Transient Authentication, in which a small hardware token (Mobile Phone) continuously authenticates the userís presence over a short-range, wireless link to the machine through which the user is accessing cloud. This machine in turn provides this authentication information to cloud. When the user departs, the token and machine lose contact and the machine stops exchanging the information with cloud making the data secure. We show how to leverage this authentication framework to secure sensitive and confidential data on to the cloud.